Iron Content Affects Lipogenic Gene Expression in the Muscle of Nelore Beef Cattle

Abstract

Iron (Fe) is an essential mineral for metabolism and plays a central role in a range of biochemical processes. Therefore, this study aimed to identify differentially expressed (DE) genes and metabolic pathways in Longissimus dorsi (LD) muscle from cattle with divergent iron content, as well as to investigate the likely role of these DE genes in biological processes underlying beef quality parameters. Samples for RNA extraction for sequencing and iron, copper, manganese, and zinc determination were collected from LD muscles at slaughter. Eight Nelore steers, with extreme genomic estimated breeding values for iron content (Fe-GEBV), were selected from a reference population of 373 animals. From the 49 annotated DE genes (FDR<0.05) found between the two groups, 18 were up-regulated and 31 down-regulated for the animals in the low Fe-GEBV group. The functional enrichment analyses identified several biological processes, such as lipid transport and metabolism, and cell growth. Lipid metabolism was the main pathway observed in the analysis of metabolic and canonical signaling pathways for the genes identified as DE, including the genes FASN, FABP4, and THRSP, which are functional candidates for beef quality, suggesting reduced lipogenic activities with lower iron content. Our results indicate metabolic pathways that are partially influenced by iron, contributing to a better understanding of its participation in skeletal muscle physiology.

Widespread modulation of gene expression by copy number variation in skeletal muscle

“…A high level of variation within as well as between breeds has been observed before for several MHC genes 19 , 22 . In previous studies, we have also found BLA - DQB differentially expressed in genetically divergent sample groups for iron content 23 and residual feed intake 24 .

Figure 2 Local effects of copy number variation: significant dosage effects of MHC genes.

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Increased expression of thyroid hormone responsive protein (THRSP) is the result but not the cause of higher intramuscular fat content in cattle

“…A compensatory physiological mechanism was suggested as possible explanation for a higher expression of THRSP in low-starch fed animals of the second study 27. In a recent investigation, significant down-regulation of THRSP was found in steers with a low estimated genomic breeding value for iron content of the meat compared to those with a high one 52. The authors assumed a reduced lipogenic activity in muscle with lower iron content.…”

Diferentes taxas de crescimento após período de restrição alimentar alteram atributos de qualidade da carne e o transcriptoma de vacas

“…Entendendo o fato que o músculo esquelético pode ser afetado pelo crescimento, pela mudança na taxa de síntese de DNA e RNA (BEERMANN, 2004), o que consequentemente proporciona uma acreção proteica e renovação de proteínas miofibrilares (KOOHMARAIE et al, 2002), elucidar mecanismos genéticos, relações entre genes e suas funções torna-se importante para compreensão do desenvolvimento dos animais, bem como processos biológicos e vias metabólicas que determinam fenótipos de qualidade da carne. Alguns trabalhos têm usado essa técnica com êxito em pesquisas envolvendo bovinos de corte, tanto para características como desenvolvimento muscular, gordura intramuscular e perfil de ácidos graxos (BALDWIN VI et al 2012;CESAR et al, 2016;DINIZ et al, 2016;SILVA-VIGNATO et al, 2017). Essa técnica também tem sido usada no estudo do músculo de animais em ganho compensatório de animais jovens (COSTA et al 2017;KEOGH et al 2016a), mostrando mudanças importantes na expressão de genes envolvidos em rotas de renovação de tecido conjuntivo, hipertrofia do tecido muscular e diferenciação de tipo de fibras.…”